Apparatus for hardening strips of metal



(No Model.) 3 Sheets-Sheet 1.

J. LOGAN & M. H. STEVENS. ABPARATUS FOR HARDENING STRIPS or METAL.

No. 484,968. Patented Oct. 25, 1892.

Wi'TN 55555: INVENTURi' Tn: News PETERS 1:0,, Pnoroumu, WASHKNGTON u c 3 Sheets-Sheet 2. J. LOGAN & M. H. STEVENS. APPARATUS FOR HARDENING STRIPS 0F METAL.

Patented Oct. 25,1892.

(No Model.)

(No Model.) 3 SheetsSheet 3.

J. LOGAN & M. H. STEVENS. APPARATUS FOR HARDENING STRIPS 0P METAL.

No. 484,968. A Patented Oct. 25, 1892.

ggia a E511 N gr/ENTERS QWAQM' 'UNITED STATES PATENT OFFICE.

JOHN LOGAN AND MILTON H. STEVENS, OF WALTHAM, MASSACHUSETTS.

APPARATUS FOR HARDENING STRIPS OF METAL.

SPECIFICATION forming part of Letters Patent No. 484,968, dated October 25, 1892. Application filed October 26, 1891. Serial No. 409,860. (No model.)

. preliminary to its subjection to a liquid bath,

as of oil or water. It will be understood that in order to secure a positive uniformity in the hardness of the metal in its entire length it must have auniform degree of heat at the instant of its subjectionto the chilling-bath of liquid, which must also be maintained at a constant temperature. Formerly in the manufacture of watch-mainsprings it was customary to cut the metal strips into lengths atrifle in excess of that of a finished spring, and when in readiness for the process of hardening they were carefully coiled in a fiat involute spiral, the successive coils being separated from each other by the intervention of small Wires, which also served to bind and hold the completed coil in place. These coils were then placed upon asort of table or rack, which was capable of being revolved or turned upon a stud or pin affixed at the end of a long handle of iron. This was then placed in a large muffle or furnace, ordinarily heated by coal or coke and by means of an iron rod, the above-mentioned table was at intervals moved around for the purpose of securing, so far as possible, a uniformity of heat in all portions of the coil of metal. When sufficiently heated, the whole was removed from the furnace and the coil plunged into a bath of tallow, oil, or Water, or any suitable compound, and when cool the binding-wires were removed and the variouslengths of steel separated. If the entire lot had by carefulness and skill been evenly hardened, it would be found that the strips near the center of the coil had quite a different curve from those near the outside of the coil and were much more likely to be broken while in their state of brittleness.

A great improvement in the foregoing method was embodied in the patent of John Logan, No. 297,610, of April 29, 1884, which consisted in tightly coiling long strips of the steel and inclosing them in round boxes or closed muffles, the outer end of the strip projecting through an opening in the periphery of the box. This muffle was then carefully heated in any suitable furnace, preferably using gas as a fuel, and when properly heated the entire strip was withdrawn from *the mufiie into and through the cooling-bath, being wound upon any suitable drum or bobbin.

Our invention is an improvement upon the last-mentioned process, and by it the coiling of the several steel strips is rendered needless, as is also the use of the muffles. A uniformity of heat is also secured, the hardening process greatly expedited, and a uniformity in quality, as well as a ready adaptation to large or small stock, is provided for; To this end We secure the proper heating of the steel strips by a rolling contact with the periphery of two or more revolving drums or wheels, which are maintained at the desired degree of heat by flames of gas, which impinge on the interior surface of the hollow drums or wheels, as shown in the accompanying drawings, in which Figure 1 is an end elevation of part of the contrivance. Fig. 2 is a longitudinal central section of the same. Fig. 3 is a transverse section of the same, showing, also, partially in section, the chilling bath appliances.

A represents a platform or carriage mounted on wheels at, fitted to run on an iron track or way b.

13 represents a suitable frame, in which are mounted two shafts or arborsO and 0, one of which is preferably located over the other. One of these shafts carries a worm-gear c, which is driven by a worm cl. The second shaft receives motion from the first, either by means of spur-gears or a crossed belt, as shown herein. On adjacent ends of shafts are mounted hollow drums D and D, which are removably affixed to the shafts. In the interior of each of the drums are located compound gas-burners E and E.

F is a suitable covering or housing, preferably lined with fire-brick and secured to the movable carriage.

F is a similar housing firmly fixed to the iron track.

G is'a gas-pipe connecting with burners E and E. His a wind or an air-blast pipe leadmg tothe same burner.

I represents a spool or bobbin containing the steel strips to be hardened.

K is a guide-roll afiixed to housing F.

L represents the tank or oil-bath, having an inclined apron Z, in which are suitable guides.

N is a constant stream of oil flowing upon the apron Z, thence into the tank, whence it is carried by an overflow-pipe f to a suitable cooling-chamber, from which it is again drawn or forced through a pipe f by means of a pump, of any known construction adapted to the purpose, and again discharged upon the apron.

O'is the steel strip, moving in the directions ndicated by the arrows. These strips are JOIIlfld end to end, so that when once started the strip may be kept in constant motion until the bobbin I is emptied. It will be observed that while the housing F isstationary F is movable, being carried by the carriage. Thisarrangement readily allows the removal or replacing of the drums and also gives convenient access to the burners.

This description of the machine renders very apparent its mode of operation, which 1s briefly as follows: The movable carriage is rolled back from the fixed housing, exposing the gas-burners, which are then lighted, and the proper combination of air and gas adgusted by means of the ordinary controlling valves or cocks. The carriage is then moved back into place and the drums put in motion, as previously described. The steady revolution of the drums insures a uniform distribution of heat over the entire circumference of the drums, and when they have been brought to the desired degree of heat the carriage is again moved back a shortdistance, and the strip of steel to be hardened is passed down under the lower drum and across and over the top one, thence through the oilstream and between guide-rolls and into and through the oil-bath and wound upon another reel or bobbin. The speed of the revolving heating-drums will of course govern the process of the wire, and this will beso regulated as to insure a proper degree of heat, which heat can also be governed by manipulation of the gas and air valves. It will be apparent that the heavier the strip the slower must it be moved or the greater must be the heat of the drums. The speed of the latter may be varied by any convenient means, as by the employment of the Evans frictioncones. By omitting the chilling-bath the same apparatus may be used for the process of annealing, and we do not limit ourselves to two drums or burners, as any number may be used without departing from the spirit of theinvention. I

Having now described our invention, we

desire to claim-- more revolving drums, each having a burner within it arranged within the housing, as set forth.

2. The combination, with a divided housing provided with openings for the passage of a strip or ribbon of material, of one or more revolvingdrums, each having a burner within it arranged within the housing, and a movable carriage with which a divided part of the housing is connected, as set forth.

3. The combination, with a divided hous-,

ingprovided with openings for the passage of a strip or ribbon of material, of one or more revolving drums, each having a burner within it arranged within the housing, an apron or table over which the strip of material passes, and a pipe for discharging a continuous stream of oil or other liquid upon the material, as set forth.

In testimony whereof we have signed our names to this specification, in the presence of two subscribing witnesses, this 10th dayof October, A. D. 1891.

7 JOHN LOGAN. I

MILTON H. STEVENS. Witnesses:

ARTHUR W. CROSSLEY, A. D. HARRISON. 

